diff --git a/src/time-and-attendance/time-tracker/shifts/controllers/shift.controller.ts b/src/time-and-attendance/time-tracker/shifts/controllers/shift.controller.ts
index 789117f..3c796c5 100644
--- a/src/time-and-attendance/time-tracker/shifts/controllers/shift.controller.ts
+++ b/src/time-and-attendance/time-tracker/shifts/controllers/shift.controller.ts
@@ -22,8 +22,9 @@ export class ShiftController {
     }
 
     @Patch('update')
-    updateBatch( @Body() dtos: ShiftDto[]): Promise<Result<ShiftDto[], string>>{
-        return this.update_delete_service.updateOneOrManyShifts(dtos);
+    updateBatch( @Body() dtos: ShiftDto[], @Req() req): Promise<Result<ShiftDto[], string>>{
+        const email = req.user?.email;
+        return this.update_delete_service.updateOneOrManyShifts(dtos, email);
     }
 
     @Delete(':shift_id')
diff --git a/src/time-and-attendance/time-tracker/shifts/services/shifts-update-delete.service.ts b/src/time-and-attendance/time-tracker/shifts/services/shifts-update-delete.service.ts
index 726e216..d533954 100644
--- a/src/time-and-attendance/time-tracker/shifts/services/shifts-update-delete.service.ts
+++ b/src/time-and-attendance/time-tracker/shifts/services/shifts-update-delete.service.ts
@@ -6,21 +6,27 @@ import { Injectable } from "@nestjs/common";
 import { Normalized } from "src/time-and-attendance/utils/type.utils";
 import { ShiftDto } from "src/time-and-attendance/time-tracker/shifts/dtos/shift-create.dto";
 import { Result } from "src/common/errors/result-error.factory";
+import { EmployeeTimesheetResolver } from "src/time-and-attendance/utils/resolve-timesheet.utils";
 
 @Injectable()
 export class ShiftsUpdateDeleteService {
     constructor(
         private readonly prisma: PrismaService,
         private readonly typeResolver: BankCodesResolver,
+        private readonly timesheetResolver: EmployeeTimesheetResolver,
     ) { }
 
-    async updateOneOrManyShifts(shifts: ShiftDto[]): Promise<Result<ShiftDto[], string>> {
+    async updateOneOrManyShifts(shifts: ShiftDto[], email: string): Promise<Result<ShiftDto[], string>> {
         try {
             //verify if array is empty or not
             if (!Array.isArray(shifts) || shifts.length === 0) return { success: false, error: 'No data received' };
 
+            //check for overlap inside dto objects
+            const overlap_check = await this.overlapChecker(shifts);
+            if (!overlap_check.success) return overlap_check;
+
             //calls the update functions and await the return of successfull result or not
-            const results = await Promise.allSettled(shifts.map(shift => this.updateShift(shift)));
+            const results = await Promise.allSettled(shifts.map(shift => this.updateShift(shift, email)));
 
             //return arrays of updated shifts or errors
             const updated_shifts: ShiftDto[] = [];
@@ -50,11 +56,14 @@ export class ShiftsUpdateDeleteService {
     //_________________________________________________________________
     //                              UPDATE
     //_________________________________________________________________
-    async updateShift(dto: ShiftDto): Promise<Result<ShiftDto, string>> {
+    async updateShift(dto: ShiftDto, email): Promise<Result<ShiftDto, string>> {
         try {
+            const timesheet = await this.timesheetResolver.findTimesheetIdByEmail(email, toDateFromString(dto.date));
+            if (!timesheet.success) return { success: false, error: ' timesheet not found' }
+
             //finds original shift
             const original = await this.prisma.shifts.findFirst({
-                where: { id: dto.id },
+                where: { id: dto.id, timesheet_id: timesheet.data.id },
                 select: shift_select,
             });
             if (!original) return { success: false, error: `Shift with id: ${dto.id} not found` };
@@ -69,12 +78,10 @@ export class ShiftsUpdateDeleteService {
                     + `end_time: ${toStringFromHHmm(normed_shift.data.end_time)},`
                     + `date: ${toStringFromDate(normed_shift.data.date)}.`
             };
-            const overlap_check = await this.overlapChecker(normed_shift.data);
-            if(!overlap_check.success) return { success: false, error: 'Invalid shift, overlaps with existing shifts'}
 
             //finds bank_code_id using the type
             const bank_code = await this.typeResolver.findBankCodeIDByType(dto.type);
-            if (!bank_code.success) return { success: false, error: 'No bank_code_id found' };
+            if (!bank_code.success) return { success: false, error: bank_code.error };
 
             //updates sent to DB
             const updated = await this.prisma.shifts.update({
@@ -147,28 +154,23 @@ export class ShiftsUpdateDeleteService {
         return { success: true, data: { date, start_time, end_time, bank_code_id: bank_code_id.data } };
     }
 
-    private overlapChecker = async (dto: Normalized): Promise<Result<void, string>> => {
-        
-        const existing_shifts = await this.prisma.shifts.findMany({
-            where: {  date: dto.date },
-            select: { id: true, date: true, start_time: true, end_time: true },
-        });
-        for (const existing of existing_shifts) {
-            const existing_start = toDateFromString(existing.start_time);
-            const existing_end = toDateFromString(existing.end_time);
-            const existing_date = toDateFromString(existing.date);
-
-            const has_overlap = overlaps(
-                { start: dto.start_time, end: dto.end_time, date: dto.date },
-                { start: existing_start, end: existing_end, date: existing_date },
-            );
-            if (has_overlap) {
-                return {
-                    success: false,
-                    error: `SHIFT_OVERLAP`
-                        + `new shift:  ${toStringFromHHmm(dto.start_time)}–${toStringFromHHmm(dto.end_time)} `
-                        + `existing shift: ${toStringFromHHmm(existing.start_time)}–${toStringFromHHmm(existing.end_time)} `
-                        + `date:  ${toStringFromDate(dto.date)})`,
+    private overlapChecker = async (shifts: ShiftDto[]): Promise<Result<void, string>> => {
+        for (const shift_a of shifts) {
+            for(const shift_b of shifts){
+                if(shift_a.date === shift_b.date){
+                    const has_overlap = overlaps(
+                        { start: toHHmmFromString(shift_a.start_time), end: toHHmmFromString(shift_a.end_time) },
+                        { start: toDateFromString(shift_b.start_time), end: toDateFromString(shift_b.end_time) },
+                    );
+                    if (has_overlap) {
+                        return {
+                            success: false,
+                            error: `SHIFT_OVERLAP`
+                                + `new shift:  ${shift_a.start_time}–${shift_a.end_time} `
+                                + `existing shift: ${shift_b.start_time}–${shift_b.end_time} `
+                                + `date:  ${shift_a.date})`,
+                        }
+                    }
                 }
             }
         }